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Chapter 17
Processing of Metal Powders
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. В© 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Parts Made by Powder-Metallurgy
(b)
(c)
(a)
Figure 17.1 (a) Examples of typical parts made by powder-metallurgy processes. (b) Upper
trip lever for a commercial sprinkler made by P/M. This part is made of an unleaded brass
alloy; it replaces a die-cast part with a 60% savings. (c) Main-bearing metal-powder caps for
3.8 and 3.1 liter General Motors automotive engines. Source: (a) and (b) Reproduced with
permission from Success Stories on P/M Parts, 1998. Metal Powder Industries Federation,
Princeton, New Jersey, 1998. (c) Courtesy of Zenith Sintered Products, Inc., Milwaukee,
Wisconsin.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. В© 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Steps in Making Powder-Metallurgy Parts
Figure 17.2 Outline of processes and operations involved in making powder-metallurgy parts.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. В© 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Particle Shapes in Metal Powders
Figure 17.3 Particle shapes in metal powders, and the processes by which
they are produced. Iron powders are produced by many of these processes.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. В© 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Powder Particles
(a)
(b)
Figure 17.4 (a) Scanning-electron-microscopy photograph of iron-powder particles made
by atomization. (b) Nickel-based superalloy (Udimet 700) powder particles made by the
rotating electrode process; see Fig 17.5c. Source: Courtesy of P.G. Nash, Illinois
Institute of Technology, Chicago.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. В© 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Methods of
Metal-Powder
Production by
Atomization
Figure 17.5 Methods of
metal-powder production
by atomization: (a) gas
atomization; (b) water
atomization; (c)
atomization with a rotating
consumable electrode; and
(d) centrifugal atomization
with a spinning disk or cup.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. В© 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Mechanical Comminution to Obtain Fine Particles
Figure 17.6 Methods of mechanical comminution to obtain fine particles:
(a) roll crushing, (b) ball mill, and (c) hammer milling.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. В© 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Mechanical Alloying
Figure 17.7 Mechanical alloying of nickel particles with dispersed smaller particles. As nickel
particles are flattened between the two balls, the second smaller phase is impresses into the
nickel surface and eventually is dispersed throughout the particle due to successive flattening,
fracture, and welding events.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. В© 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Bowl Geometries in Blending
Metal Powders
(e)
Figure 17.8 (a) through (d) Some common bowl geometries for mixing or blending
powders. (e) A mixer suitable for blending metal powders. Since metal powders are
abrasive, mixers rely on the rotation or tumbling of enclosed geometries as opposed to
using aggressive agitators. Source: Courtesy of Gardner Mixers, Inc.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. В© 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Compaction
Figure 17.9 (a) Compaction of metal powder to form a bushing. The pressed-powder
part is called green compact. (b) Typical tool and die set for compacting a spur gear.
Source: Courtesy of Metal Powder Industries Federation.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. В© 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Density as a Function of
Pressure and the Effects of
Density on Other Properties
Figure 17.10 (a) Density of copper- and ironpowder compacts as a function of compacting
pressure. Density greatly influences the
mechanical and physical properties of P/M
parts. (b) Effect of density on tensile strength,
elongation, and electrical conductivity of
copper powder. Source: (a) After F. V. Lenel,
(b) IACS: International Annealed Copper
Standard (for electrical conductivity).
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. В© 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Density Variation in Compacting Metal Powders
Figure 17.11 Density variation in compacting metal powders in various dies: (a) and
(c) single-action press; (b) and (d) double-action press. Note in (d) the greater
uniformity of density from pressing with two punches with separate movements when
compared with (c). (e) Pressure contours in compacted copper powder in a singleaction press. Source: After P. Duwez and L. Zwell.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. В© 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Compacting Pressures for Various Powders
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. В© 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Press for
Compacting Metal
Powder
Figure 17.12 A 7.3-mn (825-ton)
mechanical press for compacting
metal powder. Source: Courtesy
of Cincinnati Incorporated.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. В© 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Cold Isostatic Pressing
Figure 17.13 Schematic diagram of cold isostatic pressing, as applied to forming a
tube. The powder is enclosed in a flexible container around a solid-core rod.
Pressure is applied isostatically to the assembly inside a high-pressure chamber.
Source: Reprinted with permission from R. M. German, Powder Metallurgy Science,
Metal Powder Industries Federation, Princeton, NJ; 1984.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. В© 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Capabilities Available from P/M Operations
Figure 17.14 Capabilities, with respect to part size and shape complexity, available form
various P/M operations. P/F means powder forging. Source: Courtesy of Metal Powder
Industries Federation.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. В© 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Hot Isostatic Pressing
Figure 17.15 Schematic illustration of hot isostatic pressing. The pressure
and temperature variation versus time are shown in the diagram.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. В© 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Valve Lifter for Diesel Engines
Figure 17.16 A valve lifter for heavy-duty diesel engines produced form a hotisostatic-pressed carbide cap on a steel shaft. Source: Courtesy of Metal Powder
Industries Federation.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. В© 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Powder Rolling
Figure 17.17 Schematic illustration of powder rolling.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. В© 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Spray Deposition
Figure 17.18 Spray deposition (Osprey Process) in which molten metal is
sprayed over a rotating mandrel to produce seamless tubing and pipe.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. В© 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Sintering Time and Temperature for Metals
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. В© 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Mechanisms for Sintering Metal Powders
Figure 17.19 Schematic illustration of two mechanisms for sintering metal
powders: (a) solid-state material transport; and (b) vapor-phase material transport.
R = particle radius, r = neck radius, and p = neck-profile radius.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. В© 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Mechanical Properties of P/M Materials
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. В© 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Comparison of Properties of Wrought and Equivalent P/M Metals
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. В© 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Mechanical Property Comparisons for Titanium Alloy
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. В© 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Design Considerations for P/M
•
•
•
•
•
•
•
•
•
The shape of the compact must be kept as simple and uniform as possible.
Provision must be made for ejection of the green compact without damaging the
compact.
P/M parts should be made with the widest acceptable tolerances to maximize tool life.
Part walls should not be less than 1.5 mm thick; thinner walls can be achieved on
small parts; walls with length-to-thickness ratios above 8:1 are difficult to press.
Steps in parts can be produced if they are simple and their size doesn’t exceed 15%
of the overall part length.
Letters can be pressed if oriented perpendicular to the pressing direction. Raised
letters are more susceptible to damage in the green stage and prevent stacking.
Flanges or overhangs can be produced by a step in the die.
A true radius cannot be pressed; instead use a chamfer.
Dimensional tolerances are on the order of В±0.05 to 0.1 mm. Tolerances improve
significantly with additional operations such as sizing, machining and grinding.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. В© 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Die Design for Powder-Metal Compaction
Figure 17.20 Die geometry and design features for powder-metal compaction.
Source: Courtesy of Metal-Powder Industries Federation
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. В© 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Poor and Good
Designs of P/M
Parts
Figure 17.21 Examples of P/M
parts showing poor and good
designs. Note that sharp radii
and reentry corners should be
avoided and that threads and
transverse holes have to be
produced separately by
additional machining operations.
Source: Courtesy of Metal
Powder Industries Federation.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. В© 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Design Features for Use with Unsupported
Flanges or Grooves
Figure 17.22 (a) Design features for use with unsupported flanges. (b) Design
features for use with grooves. Source: Courtesy of Metal Powder Industries Federation.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. В© 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
Use of Smooth Transitions in Molds
Figure 17.23 The use of smooth transitions in molds for powder-injection
molding to ensure uniform metal-powder distribution throughout a part.
Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid.
ISBN 0-13-148965-8. В© 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved.
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